Posted on 05/02/2003 2:12:33 PM PDT by CathyRyan
The SARS virus is mutating rapidly, developing at least two forms, which could complicate efforts to develop a solid diagnosis and a vaccine, researchers said Friday.
"This rapid evolution is like that of a murderer who is trying to change his fingerprints or even his appearance to try to escape detection," said Dr. Dennis Lo, a chemical pathologist at the Chinese University of Hong Kong.
Researchers at the university said they have determined the genetic sequences of virus samples taken from 11 SARS patients, and that by late March there were two forms of the virus present in Hong Kong.
Lo said one strain was detected in a woman whose illness was linked to an outbreak caused by a mainland Chinese man who spread SARS to others at a Hong Kong hotel. The other strain came from a Hong Kong man believed to have caught it in the mainland border city of Shenzhen.
"We have shown that the SARS coronavirus is undergoing rapid evolution in our population," Lo said. But he noted that more work is needed before researchers can say whether the virus has become more infectious and lethal.
Researchers also need to find out whether people who get SARS from one strain can develop immunity to other strains, he said. If not, finding ways to better diagnose it and to develop a vaccine could be more difficult.
The World Health Organization says there's no evidence that the mutations have any effect on the disease itself. WHO scientists also say it's not surprising the SARS bug shows genetic changes, because the coronavirus family is prone to mutations.
A U.S. coronavirus expert, David Brian, at the University of Tennessee in Knoxville, agreed that a rapidly mutating SARS virus could complicate work toward a vaccine and reliable diagnostic tests.
The crucial question is where the mutations occur in the SARS virus genome, he said. If they affect the shape of an outer protein on the virus, it could hamper vaccines, which rely on training the immune system to recognize particular protein shapes, he said.
As for diagnosis, it is based on specific features of the bug's genetic sequence. So if one of the crucial features is removed by mutation, the detection kit becomes less sensitive to recognizing the virus, he said.
Hong Kong scientists are also concerned that the virus may survive in an infected person's body for at least a month after recovery. Doctors are urging patients to avoid personal contact such as hugging and kissing when they go home.
"The virus still exists in the patients' urine and stool after they were discharged. It will persist for at least another month or maybe even longer," said Dr. Joseph Sung, head of the Department of Medicine at the Chinese University of Hong Kong.
What's more, scientists here also fear that 12 people may have relapsed. The new findings raise questions as to how doctors can tell whether a patient has fully recovered, underscoring the difficulty health authorities face in tackling this new disease.
Sung, who works at the Prince of Wales Hospital, which was hard-hit by SARS, has monitored the cases of about 240 recovered SARS patients. He said none has spread the disease to others.
If recovered patients wear masks, avoid close contact with family members and are particularly careful about toilet hygiene, things should be "quite safe" in their households, he said.
Sung believes the virus can survive in the environment longer than a day. "If your saliva gets on a table surface, don't assume that it will be all right after it dries up," he said.
Dr. David Heymann, WHO's chief of communicable diseases, said the relapses are disappointing, and it's not clear what caused them. He said he hadn't heard of similar reports outside Hong Kong.
"We don't yet have the data ... as to exactly what has happened, what these people were treated with," Heymann said. He said one theory is that some relapses may have happened because patients stopped taking steroids too quickly. The steroid therapy is being prescribed in Hong Kong.
Heymann said in some other infectious diseases, it's not uncommon to find virus in body excretions after a patient's symptoms are gone.
"So it's not a new phenomenon that viruses remain, but certainly a relapse is concerning," he said.
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EDITOR'S NOTE: Associated Press writer Helen Luk in Hong Kong and Science Writer Malcolm Ritter in New York contributed to this story.
SARS-1 and SARS-2 ?
The exodus from Beijing is only about a week old, and the soonest we could expect to hear evidence of its spread to other provinces is several days from now. And that's only if the information is accurate and timely.
I don't think a SARS vaccine will ever be developed simply because of the mutations and the nature of the virus. It's the common cold, with a vicious streak.
Some city doctors do not agree with WHO
By: Madhurima Nandy
May 2, 2003
Mumbai’s medical fraternity is divided over the World Health Organisation’s (WHO) theory that poor sanitation and hygiene conditions may have helped Indians develop immunity towards Sars.
While some say the WHO assessment is accurate, others feel it is an untested hypothesis yet.
Dr G V Koppikar, dean, Nair Hospital, said she was inclined to support WHO. “Sars is caused by a corona virus. Indians are constantly exposed to various corona viruses, including the one that causes Sars.
Other viruses like the para-influenza virus or para-myxo virus are also common. This may have strengthened our immunity system,” she noted.
However, Dr Rohini Chowgule, chest physician at Bombay Hospital and director, Indian Institute of Environmental Medicines, said a better immunity system may not be the reason Indians have stayed relatively unharmed.
If that were true, Indians would be immune to malaria and tuberculosis too, she stressed.
Dr Jayesh Bellare, head of the BJM School of Biosciences and Biomedicines, IIT Mumbai, said it was likely that extensive exposure to poor hygiene conditions and viral diseases made Indians immune to the respiratory illness.
But he cautioned: “It is only a hypothesis, just as there is a crazy hypothesis that Sars cultivates in temperate rather than tropical climates.”
However, the experts are agreed that the Sars virus that has arrived in India is mutated and thus less dangerous.
While Hong Kong has reported 1,500 confirmed cases and 133 deaths, China has recorded over 2,000 cases and 131 deaths due to Sars.
There has yet been no death in India due to Sars. Three confirmed Sars patients have been discharged from hospitals, and yesterday’s announcement by the WHO that India was a Sars-free nation and that the cases recorded so far did not fit the WHO definition of the disease has raised a question mark over the 20 “confirmed” cases.
Dr Koppikar and Dr Bellare said the virus has certainly reached India in a more attenuated form.
Dr Chowgule said, “The only genuine case of Sars is that of the D’Silvas in Pune, as it has infected nine other people. The other cases were probably only suspected ones.”
Health Minister Digvijay Khanvilkar, for his part, welcomed the WHO hypothesis.
He said: “The National Institute of Virology reports show the condition of patients has drastically improved. We have been able to tackle the disease.”
The WHO hypothesis
• Indians probably have an immunity to the corona virus to which Sars belongs
• All suspected cases show only mild symptoms of Sars
• It could well be a case of cross-immunity of the Sars virus and other corona viruses which cause cold
• The Sars virus may have reached India in a mutated, less virulent form
By Chen Fu-min ³¯ºÖ¥Á
Friday, May 02, 2003,Page 8
The importance of severe acute respiratory syndrome (SARS) has outweighed that of the US-Iraq war in people's minds. SARS might appear terrifying, but the number of fatalities so far stands at only a few hundred. If those in power can respect professionalism, methods for diagnosing, curing and preventing SARS should be developed very quickly through international coopera-tion. At the moment, calming people's feelings is the most important thing. Creating panic among ourselves will only cause serious damage to the country.
SARS is caused by a new type of coronavirus, which rapidly sabotages the human body's immune system and starts to reproduce. It makes inroads right into the lungs. It is not yet known whether the virus is extremely destructive during reproduction, or whether the body's immune system reacts so drastically to it that it damages the internal organs, causing breathing failure and even death.
The SARS virus apparently changes very quickly -- six strains have been identified so far. We also know that the coronavirus cannot stand heat. The children who often come down with colds might be relatively less prone to SARS or might have lighter symptoms if they do get infected. We also know that only by staying in a closed room or having close contact with patients can one easily contract the disease. It means that it takes a large quantity of virus cells for one to get infected.
I therefore offer the following viewpoints.
First, according to the basic principle that organisms always seek to prolong their lives, we can believe that the SARS virus has no intention of killing its host because the virus cannot form an independent cell by itself and it must rely on the host cell for survival. It keeps mutating in order to lengthen its life. Therefore, we can reasonably believe that it will become milder and milder, allowing the host to stay alive to spread the virus.
Second, since the cause of SARS is coronavirus, the modes of transmission should be akin to those of the flu. The quantity of virus cells and one's natural immunity should be important factors in whether one will be infected.
In terms of prevention, engaging in more outdoor activities and staying away from SARS-affected patients is the best policy. Not going to high-risk areas and avoiding contact with patients is the second best method. If one must go to dangerous areas or come into contact with patients, one must wear masks and frequently wash one's hands.
Third, diagnosing and curing a disease early is the golden rule. Conducting a self-evaluation and seeking medical help as early as possible can save lives. The flu caused by another coronavirus does not cause a fever, which means the virus cannot stand heat. SARS patients have a fever because the mutated coronavirus triggers overly strong human immune reactions. We can reasonably deduce that immediate exposure to sunlight or a hot bath after being exposed to the SARS virus, or receiving fevertherapy when symptoms begin to appear, will achieve good results.
Fourth, to avoid infection, the government should encourage people to spend more time at home or outdoors. Use electronic communications more and reduce the number of gatherings. Use mass transportation systems less.
And fifth, humans normally can recover from a virus-induced disease. Patients should seek medical treatment to protect their lung tissue as early as possible.
In the long run, a standard remedy will appear. We even can expect the virus to become milder. People do not have to panic.
Chen Fu-min is director of the department of obstetrics and gynecology at Taipei Chungshan Hospital and the hospital's chairman.
http://www.taipeitimes.com/News/edit/archives/2003/05/02/204349
I'll go with the untested hypothesis.
Personally, I think this is getting a lot more attention than it needs.
Time will tell.
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